The present invention relates to an industrial process for preparing low-foaming nonionic surfactants and more particularly to a process for preparing ether-capped poly(oxyalkylated) alcohol surfactants which have superior spotting and filming benefits in dishwashing and hard surface cleaning applications, as well as suds suppression in detergent compositions.
Ether-capped poly(oxyalkylated) alcohols can be prepared using various catalysts, such as Lewis acids. However, for industrial production, metallic catalysts, such as stannic chloride is preferred. In addition to being an excellent catalyst for the reaction of a glycidyl ether with ethoxylated alcohol, metallic catalysts are economical and readily available in commercial bulk quantities. They also offer safety and ease of handling advantages on an industrial scale versus alternative catalysts. One important disadvantage for metallic catalysts is that the soluble metallic residue component of the catalyst, such as tin residues when is the catalyst SnCl4, resulting from there use as reaction catalyst, generally cannot be tolerated above about 100 ppm in many cleaning formulations and applications and these residues are difficult and expensive to remove from ether-capped poly(oxyalkylated) alcohol compositions. Successful laboratory approaches to removal of residual metallic catalyst component, such as the use of a silica gel plug and eluting with a 5% methanol in dichloromethane solution leads to complexity and high cost on an industrial production scale. Due to the surfactant properties of the ether-capped poly(oxyalkylated) alcohol, water washing for metallic catalyst component removal leads to emulsification problems leading to complex organicxe2x80x94aqueous separations.
Consequently, the problem remains that there is no commercially viable or industrial scale process for the removal of these metallic catalyst component residues from the ether-capped poly(oxyalkylated) alcohol compositions.
U.S. Pat. No. 4,272,394, issued Jun. 9, 1981, U.S. Pat. No. 5,294, 365, issued Mar. 15, 1994 U.S. Pat. No. 4,248,729, issued Feb. 3, 1981; U.S. Pat. No. 4,284,532, issued Aug. 18, 1981; U.S. Pat. No. 4,627,927, issued Dec. 9, 1986; U.S. Pat. No. 4,790,856, issued Dec. 13, 1988; U.S. Pat. No. 4,804,492, issued Feb. 14, 1989; U.S. Pat. No. 4,770,815, issued Sep. 13, 1989; U.S. Pat. No. 5,035,814, issued Jul. 30, 1991; U.S. Pat. No. 5,047,165, issued Sep. 10, 1991; U.S. Pat. No. 5,419,853, issued May 30, 1995; U.S. Pat. No. 5,294,365, issued Mar. 15, 1994; GB Application No. 2,144,763, published Mar. 13, 1985; GB Application No. 2,154,599, published Sep. 9, 1985; WO Application No. 9,296,150, published Apr. 16, 1992; WO 94/22800, published Oct. 13, 1994, WO 93/04153, published Mar. 4, 1993, WO 97/22651, published Jun. 26, 1997, EP Application No. 342,177, published Nov. 15, 1989 and xe2x80x9cGlyceryl Bisether Sulfates. 1: Improved Synthesisxe2x80x9d Brian D. Condon; Journal Of the American Chemical Society, Vol. 71, no. 7 (July 1994).
A process for removing metallic catalyst component residues from the ether-capped poly(oxyalkylated) alcohol reaction product has been discovered that is simple and economical to practice on an industrial scale. It has been discovered that selected aqueous solutions can be used to effectively extract the metallic catalyst component residues from ether-capped poly(oxyalkylated) alcohol while avoiding oil and water phase emulsification. This extraction method of purification avoids organic solvents, costly process aids, process complexity and provides a simple, economic industrial route to remove the metallic catalyst component residues in ether-capped poly(oxyalkylated) alcohols to below about 100 ppm. This residue extraction can be carried out as either a batch or continuous process. Furthermore, the residue can be removed in a single or multiple extraction steps.
In accordance with a first aspect of the present invention, a process for preparing an ether-capped poly(oxyalkylated) alcohol surfactant is provided. The surfactant has the formula:
R1O[CH2CH(R3)O]xCH2CH(OH)CH2OR2
wherein R1 and R2 are linear or branched, saturated or unsaturated, aliphatic or aromatic hydrocarbon radicals having from about 1 to about 30 carbon atoms; R3 is H, or a linear aliphatic hydrocarbon radical having from about 1 to about 4 carbon atoms; x is an integer having an average value from 1 to about 30, wherein when x is 2 or greater, R3 may be the same or different, independently H, or C1 to C4 in any given molecule, further wherein when x is 15 or greater and R3 is H and methyl, at least four of R3 are methyl, further wherein when x is 15 or greater and R3 includes H and from 1 to 3 methyl groups, then at least one R3 is ethyl, propyl or butyl, further wherein R2 can optionally be alkoxylated, wherein said alkoxy is selected from ethoxy, propoxy, butyloxy and mixtures thereof. The process comprises the steps of:
(a) providing a glycidyl ether having the formula: 
wherein R2 is defined as above;
(b) providing an ethoxylated alcohol having the formula: 
wherein R1, R3 and x are defined as above; and
(c) reacting the glycidyl ether with the ethoxylated alcohol to form the surfactant in the presence of a metallic catalyst;
(d) said surfactant is sparged with an inert gas, preferably N2, Ar and mixtures thereof, optionally under vacuum, preferably a vacuum in the range of 5 to 500 mmHg; and
(e) extracting said catalyst from said surfactant by at least one aqueous extraction with an aqueous solution, wherein said aqueous solution is selected from the group consisting of a from about 2% to about 15% by weight aqueous solution of sodium carbonate, a from about 2% to about 10% by weight aqueous solution of potassium carbonate, a from about 1% to about 22% by weight aqueous solution of sodium sulfate, a from about 2% to about 6% by weight aqueous solution of sodium bicarbonate, a from about 1% to about 10% by weight aqueous solution of potassium sulfate, a from about 2% to about 24% by weight aqueous solution of potassium bicarbonate, and mixtures thereof; and wherein said surfactant, after said at least one aqueous extraction, contains less than about 100 ppm of the metallic component of said metallic catalyst.
R1 and R2 are preferably a linear or branched, saturated or unsaturated, aliphatic hydrocarbon radical having from about 6 to about 22 carbon atoms and x is an integer having an average value of from about 6 to about 15.
The step of reacting the glycidyl ether with the ethoxylated alcohol is preferably conducted at a temperature of from about 50xc2x0 C. to about 95xc2x0 C. with 60xc2x0 C. to about 80xc2x0 C. even more preferred when Lewis acid catalysts are employed.
The step of providing the glycidyl ether may further comprise the step of reacting a linear aliphatic or aromatic alcohol having the formula R2OH and an epoxide having the formula: 
wherein R2 is defined as above and X is a leaving group. This reaction may also be conducted in the presence of a catalyst as defined above. The catalyst is typically employed at levels of about 0.1 mol % to about 2.0 mol % and the reaction is preferably conducted in the absence of a solvent at temperatures of from about 40xc2x0 C. to about 90xc2x0 C.
As already noted, the surfactants have advantages, including superior spotting and filming reduction benefits as well as excellent greasy soil removal, good dishcare, suds suppression and good overall cleaning.
Accordingly, it is an aspect of the present invention to provide a process for producing a low-foaming nonionic surfactant having superior spotting and filming reduction benefits as well as excellent greasy soil removal, good dishcare, suds suppression and good overall cleaning. It is a further aspect of the present invention to provide a process for producing an ether-capped poly(oxyalkylated) alcohol surfactant. It is a further aspect of the present invention to provide a low-foaming nonionic surfactant produced by the process of the present invention. These and other aspects, features and advantages will be apparent from the following description and the appended claims.
In the description of the invention various embodiments and/or individual features are disclosed. As will be apparent for the skilled practitioner all combinations of such embodiments and features are possible and can result in preferred executions of the invention.
All parts, percentages and ratios used herein are expressed as percent weight unless otherwise specified. All documents cited are, in relevant part, incorporated herein by reference.
Once again, the present invention is directed toward a process for producing a low-foaming nonionic surfactant for use in detergent compositions.
The novel surfactants of the present invention comprise ether-capped poly(oxyalkylated) alcohols having the formula:
R1O[CH2CH(R3)O]x[CH2]kCH(OH)[CH2]jOR2
wherein R1 and R2 are linear or branched, saturated or unsaturated, aliphatic or aromatic hydrocarbon radicals having from about 1 to about 30 carbon atoms; R3 is H, or a linear aliphatic hydrocarbon radical having from about 1 to about 4 carbon atoms; x is an integer having an average value from 1 to about 30, wherein when x is 2 or greater R3 may be the same or different and k and j are integers having an average value of from about 1 to about 12, and more preferably 1 to about 5, further wherein when x is 15 or greater and R3 is H and methyl, at least four of R3 are methyl, further wherein when x is 15 or greater and R3 includes H and from 1 to 3 methyl groups, then at least one R3 is ethyl, propyl or butyl, further wherein R2 can optionally be alkoxylated, wherein said alkoxy is selected from ethoxy, propoxy, butyloxy and mixtures thereof.
R1 and R2 are preferably linear or branched, saturated or unsaturated, aliphatic or aromatic hydrocarbon radicals having from about 6 to about 22 carbon atoms with about 8 to about 18 carbon atoms being most preferred. Additionally, R2 may be selected from hydrocarbon radicals which are ethoxylated, propoxylated and/or butoxylated. H or a linear aliphatic hydrocarbon radical having from about 1 to about 2 carbon atoms is most preferred for R3. Preferably, x is an integer having an average value of from about 1 to about 20, more preferably from about 6 to about 15.
As described above, when, in the preferred embodiments, and x is greater than 2, R3 may be the same or different. That is, R3 may vary between any of the alkyleneoxy units as described above. For instance, if x is 3, R3may be selected to form ethyleneoxy (EO) or propyleneoxy (PO) and may vary in order of (EO)(PO)(EO), (EO)(EO)(PO); (EO)(EO)(EO); (PO)(EO)(PO); (PO)(PO)(EO) and (PO)(PO)(PO). Of course, the integer three is chosen for example only and the variation may be much larger with a higher integer value for x and include, for example, multiple (EO) units and a much small number of (PO) units. However, when x is 15 or greater and R3 is H and methyl, at least four of R3 are methyl, further wherein when x is 15 or greater and R3 includes H and from 1 to 3 methyl groups, then at least one R3 is ethyl, propyl or butyl.
Particularly preferred surfactants as described above include those that have a low cloud point of less than about 20xc2x0 C. These low cloud point surfactants may then be employed in conjunction with a high cloud point surfactant as described in detail below for superior grease cleaning benefits.
Most preferred according to the present invention are those surfactants wherein k is 1 and j is 1 so that the surfactants have the formula:
R1O[CH2CH(R3)O]xCH2CH(OH)CH2OR2
where R1, R2 and R3 are defined as above and x is an integer with an average value of from about 1 to about 30, preferably from about 1 to about 20, and even more preferably from about 6 to about 18. Most preferred are surfactants wherein R1 and R2 range from about 9 to about 15, R3 is H forming ethyleneoxy and x ranges from about 6 to about 15.
Basically, the alcohol surfactants of the present invention comprise three general components, namely a linear or branched alcohol, an alkylene oxide and an alkyl ether end cap. The alkyl ether end cap and the alcohol serve as a hydrophobic, oil-soluble portion of the molecule while the alkylene oxide group forms the hydrophilic, water-soluble portion of the molecule.
It has been surprisingly discovered in accordance with the present invention that significant improvements in spotting and filming characteristics and, when used in conjunction with high cloud point surfactants, in the removal of greasy soils relative to conventional surfactants, are provided via the ether-capped poly(oxyalkylene) alcohol surfactants of the present invention.
It has been surprisingly discovered that the ether-capped poly(oxyalkylene) alcohol surfactants of the present invention in addition to delivering superior cleaning benefits also provide good suds control. This suds control can be clearly seen in the presence of high sudsing surfactants, such as amine oxides, or in the presence of high sudsing soils, such as proteinaceous or egg soils.
Generally speaking, the ether-capped poly(oxyalkylene) alcohol surfactants of the present invention may be produced by reacting an aliphatic alcohol with an epoxide to form an ether which is then reacted with a base to form a second epoxide. The second epoxide is then reacted with an alkoxylated alcohol to form the ether-capped poly(oxyalkylene) alcohol surfactants of the present invention. The product of the process is a purified mixture of ether-capped poly(oxyalkylene) alcohol surfactants. The present invention is also directed to the product, namely the purified mixture of ether-capped poly(oxyaLkylene) alcohol surfactants produced by the present method.
The process comprises the first step of providing a glycidyl ether having the formula: 
where R2 is defined as above. Various glycidyl ethers are available from a number of commercial sources including the Aldrich Chemical Company. Alternatively, the glycidyl ether may be formed from the reaction of a linear or branched, aliphatic or aromatic alcohol of the formula R2OH where R2 is defined as above and an epoxide of the formula: 
where X is a suitable leaving group. While a number of leaving groups may be employed in the present invention, X is preferably selected from the group consisting of halides including chloride, bromide, and iodide, tosylate, mesylate and brosylate, with chloride and bromide being even more preferred with chloride being the most preferred (e.g. epichlorohydrin).
The linear or branched alcohol and the epoxide are preferably reacted at ratios ranging from about 0.5 equivalents alcohol to 2.5 equivalents epoxide with 0.95 equivalents alcohol to 1.05 equivalents epoxide more typical under acidic conditions for catalysis purposes. The catalyst is a metallic catalyst. The term xe2x80x9cmetallic catalystxe2x80x9d, includes within its definition catalysts which include a metallic a component. This definition includes both salts, such as AlCl3, etc., and covalent compounds, such as BF3, SnCl4, etc., which include a metallic component. The metallic component includes all elements commonly know as metals, such as alkali metals, alkaline earth metals, transition metals, and Boron.
Suitable catalysts include, but are not limited to, TiCl4, Ti(OiPr)4, ZnCl2, SnCl4, SnCl2, FeCl3, AlCl3, and mixtures thereof, more preferably SnCl4. The metallic catalyst are preferably Lewis acids. Suitable Lewis acid catalysts include, but are not limited to, SnCl4, BF3, AlCl3, and mixtures thereof. The metallic components of these preferred catalysts are Ti, Zn, Fe, Sn, B, and Al. The metallic Lewis acid, are preferably employed at amounts of about 0.1 mol % to about 2.0 mol % with about 0.2 mol % to about 1.0 mol % being more typical.
While the reaction may be conducted in the presence of a suitable solvent such as benzene, toluene, dichloromethane, tetrahydrofuran, diethylether, methyl tert-butylether or the like, the reaction is preferably conducted neat or in the absence of solvent.
Lastly, the reaction is conducted at temperatures preferably ranging from about 40xc2x0 C. to about 90xc2x0 C., more preferably from about 50xc2x0 C. to about 80xc2x0 C.
Before the extraction of the catalyst from the surfactant, the surfactant is either sparged with an inert gas, preferably, nitrogen, argon or mixtures thereof or placed under a vacuum, to remove any oxygenated impurities which were formed during the reaction. These impurities are those typically associated with any ethoxylation processes, such as ethanol, ethylene glycol, diethylene glycol, etc. It is further preferred that the sparging is performed under a vacuum, preferably a vacuum in the range of 5 to 500 mmHg. It is further preferred that the sparging is performed for at least 30 minutes, more preferably at least 90 minutes. It is further preferred that the sparging is performed at a temperature of about 50xc2x0 C. to about 100xc2x0 C., more preferably at a temperature of 60xc2x0 C. to about 70xc2x0 C.
Upon completion of the reaction, the mixture is treated with a basic material to form the glycidyl ether. The basic material is preferably a strong base such as a hydroxide. Preferred hydroxides include alkali metal hydroxides with sodium being the typical choice. However, one of ordinary skill in the art will recognize that other basic materials may also be employed. The basic material is preferably added at levels of from about 0.5 equivalents to about 2.5 equivalents, with about 0.95 equivalents to about 2.0 equivalents being more preferred.
The product glycidyl ether may then be collected after optional filtration, drying and distillation according to the methods well-known in the art.
To form the surfactant, an ethoxylated alcohol having the formula: 
wherein R1 and x are defined as before in an amount of from about 0.80 to about 2.0 equivalents is combined with the metallic catalyst and heated to a temperature ranging from about 50xc2x0 C. to about 95xc2x0 C. and more preferably from about 60xc2x0 C. to about 80xc2x0 C. when a Lewis acid catalyst is employed. The glycidyl ether is then added to the mixture and reacted for from about 0.5 hours to about 30 hours, more preferably from about 1 hour to about 24 hours.
The metallic component of the catalyst is then extracted from the ether-capped poly(oxyalkylated) alcohol surfactant product by at least one aqueous extraction with an aqueous solution. The aqueous solution is selected from the group consisting of a from about 2% to about 15% by weight aqueous solution of sodium carbonate, a from about 2% to about 10% by weight aqueous solution of potassium carbonate, a from about 1% to about 22% by weight aqueous solution of sodium sulfate, a from about 2% to about 6% by weight aqueous solution of sodium bicarbonate, a from about 1% to about 10% by weight aqueous solution of potassium sulfate, a from about 2% to about 24% by weight aqueous solution of potassium bicarbonate, and mixtures thereof. The extraction may be either batch or continuous. It has surprisingly found that aqueous extractions with aqueous solutions containing salts, or combinations of salts other than those listed above do not reduce the metallic component of the ether-capped poly(oxyalkylated) alcohol surfactant product. Examples of unsuitable salts are sodium chloride, calcium carbonate, and sodium hydroxide.
Multiple extractions of the ether-capped poly(oxyalkylated) alcohol surfactant product may occur and are preferred. After the at least one aqueous extraction the ether-capped poly(oxyalkylated) alcohol surfactant product, contains less than about 100 ppm, preferably less than about 70 ppm, more preferably less than about 25 ppm, more preferably less than about 10 ppm of the metallic component of the metallic catalyst.
A representative synthetic route is demonstrated via the following diagram and examples. 